FIG. 1 is a schematic diagram showing a structure of a backlight in the prior art. As shown in FIG. 1, the backlight includes a light guide plate 1, a backplane 4, a rubber frame 2 and a membrane 3. The membrane 3 is usually fixed through bending the backplane 4. However, such a way of fixing the membrane 3 easily causes the membrane 3 to be scratched and wrinkled.